% function [] = f0825()
%     % x= [81, 70, 65,51, 76, 66, 90, 87, 61, 77];
%     % ret1 = average(x);
%     % fprintf("%d",ret1);
%     % ret2 = variance(x,ret1);
%     % fprintf("%d",ret2);
%     text2();
% end
% 
% 
% function [ret] = average(list)
%     sumnum = 0;
%     len = length(list);
%     pos = len;
%     while(pos > 0)
%         sumnum = sumnum + list(pos);
%         pos = pos - 1;
%     end
%     ret = sumnum/len;
% end
% 
% function [ret] = variance(list,averagenum)
%     sumnum = 0;
%     len = length(list);
%     sumnum = sum(list(1:len).^2); 
%     ret = ((sumnum - len*averagenum*averagenum)/(len-1)) ^(1/2);
% end
% 
% function [] = text2()
%     ERR = 10^(-8);
%     target = (1 + 5^(1/2)) / 2; 
%     old1 = 1;
%     old2 = 1;
%     nownum = 2;
%     k = 3;
%     while(abs(nownum / old1 -target) > ERR)
%         tmp = old2;
%         old2 = old1;
%         old1 = nownum;
%         nownum = tmp + old2;
%         k = k+ 1;
%     end
%     k
% end
% 





